It is often desired to maintain a radio control button in a retracted position during standby mode and then to extend the button for operating mode so that it is easy to manipulate. Such buttons are called popout controls. Usually this is accomplished by a dual position arrangement wherein the button mode is changed by pressing in and then releasing the button so that it alternately assumes a retracted position and an extended position.
A common arrangement for popout controls is shown in FIG. 1. There an open-fronted radio case 10 contains a main circuit board 12 in a horizontal plane, and a vertical keyboard 14 is supported outside the case by a front plate 16 which closes the front of the case. A trim plate 18 covers the front of the radio assembly and includes apertures for operating controls including pushbuttons 19 which connect to the keyboard. A plurality of popout controls 20 within the case 10 are mounted on a horizontal auxiliary board 22 and each control 20 has a threaded tubular part 24 which protrudes through the front plate 16 and is held in place by a nut 28. Each popout control comprises a shaft 30 extending through the trim plate 18 and having a knob 32, and a potentiometer packaged with a dual position arrangement 33 on the board 22 to control the shaft and knob position between a retracted position shown in solid lines and an extended position shown in dashed lines. The auxiliary board 22 is coupled to the main board by a cable 34 and connector 36, and the keyboard 14 is similarly coupled to the main board by a cable 38 and a connector 40. This arrangement has the drawbacks of requiring many parts such as the auxiliary board, cable and connectors required to provide the popout function and the space required in the radio case for those parts.
Commercially available popout controls lack stable support of the shaft 30. That is, when the knob is in extended position the knob can wobble from side to side. Further those controls must be assembled separately from the radio circuit boards and then later assembled into the radio. Generally prior popout controls employ a fixed follower which is engaged by a movable cam profile on a shaft which affects the linear position of the shaft.